CN107635918B

CN107635918B - Graphene doping method, graphene composite electrode manufacturing method, and graphene structure including same

Info

Publication number: CN107635918B
Application number: CN201680021660.5A
Authority: CN
Inventors: 文振山; 朴元培; 朴守范; 赵寅秀; 洪秉熙
Original assignee: LG Electronics Inc; Seoul National University Industry Foundation
Current assignee: LG Electronics Inc; Seoul National University Industry Foundation
Priority date: 2015-04-15
Filing date: 2016-04-15
Publication date: 2021-03-09
Anticipated expiration: 2036-04-15
Also published as: US10497893B2; EP3284718A4; EP3284718B1; CN107635918A; EP3284718A1; US20180083220A1; WO2016167583A1

Abstract

The present invention relates to graphene, and more particularly, to a method of modifying doped graphene using a substrate surface, a method of manufacturing a graphene composite electrode using graphene and an inorganic substance, and a graphene structure including the same. A method of doping graphene according to an embodiment of the present invention may include the steps of: forming a precursor polymer layer for doping on a substrate; and disposing graphene on the substrate on which the precursor polymer layer is formed. In addition, a method of manufacturing a graphene composite electrode according to an embodiment of the present invention may include the steps of: forming graphene on the catalyst metal; forming a transparent conductive oxide on the graphene; crystallizing the transparent conductive oxide by applying heat of 150 ℃ or more; and transferring the composite electrode consisting of graphene and transparent conductive oxide to a final substrate.

Description

Graphene doping method, graphene composite electrode manufacturing method, and graphene structure including same

Technical Field

The present invention relates to graphene, and more particularly, to a method of doping graphene using substrate surface modification, a method of manufacturing a graphene composite electrode using graphene and an inorganic material, and a graphene structure including the same.

Background

Fullerenes, carbon nanotubes, graphene, graphite, and the like are materials composed of carbon atoms. The graphene has a structure composed of a single atomic layer of carbon atoms arranged in a two-dimensional plane.

In particular, graphene exhibits excellent electrical, mechanical, and chemical properties that are extremely stable, and superior electrical conductivity, which transports electrons much faster than silicon, and conducts electricity much larger than copper. This is experimentally demonstrated and since 2004 a method of isolating graphene from graphite was discovered, a great deal of research has been conducted to date.

Such graphene attracts a great deal of attention as a basic material for circuits because it can be fabricated in a large area and exhibits electrical, mechanical and chemical stability and excellent conductivity.

In addition, in general, electrical properties of graphene vary according to the grain orientation of graphene of a predetermined thickness, and thus graphene exhibits electrical properties in a direction selected by a user, and thus, a device can be easily designed. Therefore, graphene can be effectively used for carbon-based electronic or electromagnetic devices and the like.

In general, application products such as display devices require transparent electrodes, and use extremely thick transparent conductive oxide films in order to maintain the requirements for such transparent electrodes.

However, such thick transparent electrodes may not be suitable for deposition on plastic substrates to make flexible devices and displays, and may not be suitable in terms of transparency and low surface roughness. Therefore, there is a need for alternatives thereto.

Meanwhile, recently, silicon oxide dielectrics are applied to analyze device properties of graphene. In the conventional case, since the p-type doping is obtained by doping the substrate, an undoped form obtained by additional heat treatment or self-assembled monolayer coating is used.

In addition, since there are cases where heat treatment cannot be performed or a self-assembled monolayer cannot be formed on a substrate other than silicon oxide, surface modification cannot be generally achieved. Therefore, there is a limit to the doping effect of graphene and thus a method for solving this problem is required.

Disclosure of Invention

[ problem ] to provide a method for producing a semiconductor device

An object of the present invention devised to solve the problem lies on a graphene doping method and a graphene structure including the graphene.

In addition, another object of the present invention devised to solve the problem lies on a method of modifying doped graphene using a substrate surface and a graphene structure including the graphene.

Meanwhile, another object of the present invention devised to solve the problem lies on a method of manufacturing a graphene composite electrode using graphene and a transparent conductive layer.

In addition, another object of the present invention devised to solve the problem lies on a method of manufacturing a graphene composite electrode, which can reduce the thickness of the electrode and can be applied to flexible devices and displays.

[ technical solution ] A

The object of the present invention can be achieved by providing a method of modifying doped graphene using a substrate surface, the method comprising forming a precursor polymer layer for doping on a substrate and disposing graphene on the substrate provided with the precursor polymer layer.

Here, the precursor polymer layer may include a precursor having a methyl group.

In this case, the precursor polymer layer may include a precursor having a methyl group as an end group.

In addition, the precursor having a methyl group may be a cyclohexane precursor.

In this case, the cyclohexane precursor may include at least one of cyclohexane, methylcyclohexane, and ethylcyclohexane.

Here, the substrate may be a polymer substrate.

In this case, the polymer substrate may include at least one of polyethylene terephthalate (PET), triacetyl cellulose (TAC), and Polycarbonate (PC).

Here, the formation of the precursor may be performed using plasma enhanced chemical vapor deposition.

Here, the method may further include doping the graphene.

In another aspect of the present disclosure, provided herein is a graphene structure comprising a substrate, a precursor layer having a methyl group disposed on the substrate, and graphene disposed on the precursor layer.

Here, the precursor having a methyl group may include at least one of cyclohexane, methylcyclohexane, and ethylcyclohexane.

Here, the substrate may include at least one of polyethylene terephthalate (PET), triacetyl cellulose (TAC), and Polycarbonate (PC).

In another aspect of the present invention, provided herein is a method of manufacturing a graphene composite electrode, comprising: forming graphene on the catalytic metal; forming a transparent conductive oxide on the graphene; crystallizing the transparent conductive oxide by applying heat of 150 ℃; and transferring the composite electrode including the graphene and the transparent conductive oxide to a final substrate.

Here, the method may further include doping the graphene after forming the graphene.

Here, the crystallization may be performed at a temperature of 150 ℃ to 400 ℃.

Here, the transparent conductive oxide may include at least one of ITO, IZO, ZnO, GZO, and AZO.

Here, the transferring may include: disposing a support layer on the transparent conductive oxide; removing the catalytic metal; adhering the composite electrode to the final substrate; and removing the support layer.

Additionally, the transferring may include: forming the final substrate on the transparent conductive oxide; and removing the catalytic metal.

Here, the final substrate may be a polymer substrate.

Here, the method may further include forming an organic EL layer on the graphene.

[ Effect of the invention ]

The present invention has the following effects.

The graphene disposed on the surface-modified substrate can improve electrical properties. In addition, graphene can exhibit characteristics of n-type doping or p-type doping.

Such a doping process can offset a decrease in conductivity caused by a grain defect of graphene formed on the catalytic metal (defect at a grain boundary of the metal).

In addition, in the case of additional doping through surface modification of the substrate using the polymer layer, the doping effect can be maximized.

Meanwhile, the transparent conductive layer formed on the graphene can produce a transparent composite electrode. That is, a transparent composite electrode having low resistance can be formed by organic/inorganic mixing of the graphene and the ITO layer.

Such a composite electrode is suitable for use in currently industrially available sputtering methods. This can result in a reduction 1/5 in the amount of ITO used. This is because the composite electrode is formed to have a small thickness, but satisfies all the conditions of the transparent electrode.

In addition, the ITO layer can function as a protective film for graphene. When the graphene is doped, the doping effect can be maintained for a longer time.

Meanwhile, a flexible transparent electrode can be manufactured by a composite electrode of graphene as a two-dimensional material and the ITO layer. That is, the composite electrode has conductivity and flexibility, thereby eliminating the limitation of a flexible display that cannot be overcome with only an ITO layer.

Drawings

Fig. 1 is a flow diagram illustrating an example of a method of modifying doped graphene using a substrate surface;

FIG. 2 is a schematic diagram showing a precursor having a methyl group as a terminal group;

fig. 3 and 4 are schematic cross-sectional views illustrating an example of a method of modifying doped graphene using a substrate surface;

fig. 5 to 7 are schematic sectional views illustrating examples of graphene structures modified using a substrate surface;

fig. 8 is a graph showing current properties of graphene in relation to doping properties;

FIG. 9 is a schematic diagram showing PECVD for substrate surface modification;

FIGS. 10 and 11 are schematic views illustrating a polymerization principle using plasma;

fig. 12 is a flowchart illustrating an example of a graphene composite electrode manufacturing method;

fig. 13 to 20 are schematic sectional views illustrating respective steps of manufacturing a graphene composite electrode; and

fig. 21 is a schematic view illustrating a process of forming a transparent conductive layer.

Detailed Description

Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.

However, the present invention is susceptible to various modifications and changes, and specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. The present invention should not be construed as limited to the embodiments set forth herein but includes modifications, equivalents, and alternatives falling within the spirit and scope of the present invention as defined by the appended claims.

It will be understood that when an element such as a layer, region or substrate is referred to as being "on" another element, it can be directly on the element or intervening elements may also be present.

In addition, it should be understood that although terms such as "first" and "second" may be used herein to describe elements, components, regions, layers and/or sections, the elements, components, regions, layers and/or sections should not be limited by these terms.

Fig. 1 is a flow chart illustrating an example of a method of modifying doped graphene using a substrate surface.

As shown in fig. 1, the method may include forming a precursor polymer layer for doping on a substrate (S1) and disposing graphene on the substrate provided with the precursor polymer layer (S2).

Here, the precursor polymer layer may include a polymer having a methyl group (CH)₃) A precursor of (2).

In this case, the precursor polymer layer may include a precursor having a methyl group as an end group. The precursor having a methyl group as a terminal group can improve the conductivity of graphene through an interaction between the methyl group of the precursor and the graphene, or can provide a condition for doping graphene under an optimal condition. This will be described in detail later.

The precursor having a methyl group may be a cyclohexane precursor. That is, the precursor having a methyl group may include at least one of cyclohexane, methylcyclohexane, and ethylcyclohexane.

Table 1 below shows the structure of this cyclohexane precursor.

TABLE 1

Here, the substrate may be a polymer substrate.

The polymer substrate may include at least one of polyethylene terephthalate (PET), triacetyl cellulose (TAC), and Polycarbonate (PC).

Hereinafter, the respective steps will be described with reference to fig. 1 and the corresponding drawings.

Fig. 2 is a schematic view showing a precursor having a methyl group as a terminal group, and fig. 3 and 4 are schematic cross-sectional views illustrating an example of a graphene doping method using substrate surface modification.

As shown in fig. 3, using the compound having a methyl group (CH) as shown in fig. 2₃) Forming a precursor polymer layer 2 on the substrate 1.

Here, the polymer layer 2 may be formed using Plasma Enhanced Chemical Vapor Deposition (PECVD).

Polymers like cyclohexane have the shape of a ring, but the ring is opened by plasma treatment such as Plasma Enhanced Chemical Vapor Deposition (PECVD) to generate radical molecules. Thus, a methyl group may be exposed at the end.

Thus, the polymer layer 20 having the methyl group exposed to the terminal can reinforce (modify) the surface of the substrate 1.

Such graphene 3 may be formed on a catalytic metal (not shown) and transferred onto the substrate 1 provided with the polymer layer 2.

The catalytic metal may be a metal such as Ni, Co, Fe, Pt, Au, Al, Cr, Cu, Mg, Mn, Mo, Rh, Si, Ta, Ti, W, U, V, Zr, or the like, and may be a single layer of any one thereof or an alloy of at least two thereof.

Methods of forming the graphene 3 include chemical vapor deposition such as thermal Chemical Vapor Deposition (CVD), inductively coupled plasma chemical vapor deposition (ICP-CVD), plasma-enhanced chemical vapor deposition (PE-CVD), microwave CVD, and the like. In addition, various methods such as Rapid Thermal Annealing (RTA), Atomic Layer Deposition (ALD), and Physical Vapor Deposition (PVD) may be used.

For example, chemical vapor deposition is a method of growing graphene 3 by placing a catalytic metal in a chamber (not shown), supplying a carbon source thereto, and providing appropriate growth conditions.

For example,the carbon source may be in a gaseous state such as methane (CH)₄) Or acetylene (C)₂H₂) Or a solid such as a powder or polymer, or a liquid such as a bubbled alcohol (bubbling alcohol).

In addition, various carbon sources such as ethane, ethylene, ethanol, acetylene, propane, butane, butadiene, pentane, pentene, cyclopentadiene, hexane, cyclohexane, benzene, and toluene can be used.

When a material that does not deform at high temperature is used as the substrate 1 instead of the polymer substrate, the graphene 3 can be directly formed on the substrate 10 instead of transferring the graphene 3 onto the substrate 1.

As described above, the substrate 1 may include a polymer containing at least one of polyethylene terephthalate (PET), triacetyl cellulose (TAC), and Polycarbonate (PC). For example, the substrate 10 may be formed using any one of PEC, TAC, and PC.

As shown in fig. 4, graphene 3 may be disposed on a substrate 1 provided with a polymer layer 2.

That is, the substrate 1 may be a flexible substrate, and the graphene 3 disposed on the flexible substrate may be used as an electrode of a flexible device.

Thus, when the graphene 3 is disposed on the surface-modified substrate 1, the graphene 3 is methyl-doped, thereby improving electrical properties.

Furthermore, this doping effect may be an n-type doping or a p-type doping.

Fig. 5 to 7 are schematic cross-sectional views showing examples of graphene structures surface-modified using a substrate.

That is, as shown in fig. 5, graphene 3 is disposed on a substrate 1, and the substrate 1 is surface-modified by a polymer layer 2 having a methyl group at its end, thereby producing a graphene structure having improved electrical properties, i.e., doping effect.

In addition, as shown in fig. 6, an additional doping layer 4 may be further included on the graphene structure having the structure shown in fig. 5.

That is, the graphene 3 disposed on the surface-modified substrate 1 may improve electrical properties through an additional doping process. In addition, as described above, the graphene 3 may exhibit n-type doping or p-type doping properties.

Such a doping process can offset the decrease in conductivity caused by the crystal grain defects of graphene formed on the catalytic metal (defects at the grain boundaries of the metal).

That is, the material of the graphene 3 is replaced with the dopant material contained in the doped layer 4, thereby generating carriers. Therefore, the carrier density can be increased.

The dopant for doping may include an organic dopant, an inorganic dopant, or a combination thereof. For example, a gas or a solution of nitric acid and a material containing the same may be used. In particular, gas phase doping using a gas may be more advantageous.

In addition, specifically, examples of such a dopant include NO₂BF₄、NOBF₄、NO₂SbF₆、HCl、H₂PO₄、CH₃COOH、H₂SO₄、HNO₃PVDF, perfluorosulfonic acid, AuCl₃、SOCl₂、Br₂、CH₃NO₂One or more of dichlorodicyanoquinone, oxone, dimyristoyl phosphatidylinositol and trifluoromethanesulfonyl imide.

Meanwhile, as shown in fig. 7, surface modification of the substrate 1 may be performed on both sides of the substrate 1. That is, the precursor polymer layer 2 is formed on both surfaces of the substrate 1, and the graphene 3 is disposed on the polymer layer 2.

Thus, as described above, the graphene 3 disposed on the substrate 1 surface-modified by the polymer layer 2 may exhibit greatly improved electrical properties.

Fig. 8 is a graph showing current properties of graphene related to doping properties. In addition, fig. 9 is a schematic view showing a PECVD process for performing substrate surface modification, and fig. 10 and 11 are schematic views showing a polymerization principle using plasma by PECVD.

Hereinafter, a process of substrate surface modification will be described with reference to fig. 8 to 11.

As described above, the surface modification of the substrate 1 can be performed by PECVD.

As shown in fig. 9, the PECVD apparatus includes a chamber 100, and an electromagnetic coil 12 and an RF power source 13 for generating plasma disposed in the chamber 100, wherein the plasma is generated on a chuck 11 on which a substrate 1 is loaded.

Backside cooling helium gas is supplied to the lower portion of the chamber 100 to lower the temperature of the substrate.

In fig. 9, the process gas is supplied from the upper portion, and the reacted gas (by-product) is discharged from the lower portion by a pump (not shown).

According to this PECVD method, a process gas is adsorbed on the surface of the substrate 1 cooled by the backside cooling helium gas, and the process gas activated by plasma reacts with the deactivated process gas to produce a polymer layer.

Here, the deposition on the substrate 1 is considered to be adsorption of the process gas due to the orientation of the plasma and the low surface temperature of the substrate 1.

Hereinafter, the reaction principle of forming the polymer layer will be described.

In FIG. 10, M_iDenotes the polymer produced from i M molecules. Thus, the subscript "i" refers to the number of molecules (e.g., k, j) that the polymer has.

In addition, the dots represent free radical forms.

One dot represents a single radical and two dots represent two radicals.

Due to the high reactivity of the free radicals, the free radicals are able to generate bonds by reacting with other molecules or free radicals.

Here, "+" indicates a reaction between two materials. The product obtained by the reaction between the two materials is arranged in the direction of the arrow, and a bond is generated after the reaction.

Further, "-" means that a bond between molecules is formed.

By such a process, the polymer layer 2 can be formed by plasma.

Referring to fig. 11, in the case of cyclohexane having a ring shape, the ring of cyclohexane is opened by plasma treatment under a hydrogen atmosphere in a principle similar to that described in fig. 10, thereby forming radical molecules.

The formed radical molecules having various structures undergo molecular weight increase as the reaction occurs in the manner as described with reference to fig. 10.

By such a process, the precursor polymer layer 2 having a methyl group as a terminal group is uniformly formed on the substrate 1, and the polymer layer 2 can greatly improve the properties of the substrate 1.

Fig. 8 shows the properties of graphene when using a polymer layer 2 with chain precursors such as methyl groups. It is known that the doping effect is maximized when the minimum value of the current curve reaches around 0V.

As shown in fig. 8, the minimum value of the current curve reaches about 0V. When the graphene 3 is disposed on the polymer layer 2, the electrical properties of the graphene 3 can be improved by bonding with the polymer layer 2.

In addition, by surface modification of the substrate 1 using the polymer layer 2, in the case of performing additional doping, the effect of doping can be maximized.

In the present embodiment, an example for the polymer layer 2 including the doping property of the conductivity enhancement has been described, but various properties can be improved depending on the type of the polymer.

For example, the functional group may be changed according to purposes, and other properties of graphene may be improved according to the functional group used.

As a result, the surface of various substrates can be modified rapidly at low cost by using a polymer layer containing an organic precursor.

The graphene may be deposited on a flexible insulating material that replaces conventionally used silicon oxides that are not suitable for flexible devices and is therefore advantageously suitable for flexible devices.

In addition, a graphene structure having high permeability can be manufactured, and thus is suitable for optical devices, displays, and the like.

Fig. 12 is a flowchart illustrating an example of a graphene composite electrode manufacturing method.

As shown in fig. 12, the method for manufacturing the graphene composite electrode includes: forming graphene on the catalytic metal (S10); forming a transparent conductive layer on the graphene using a transparent conductive oxide (S20); crystallizing the transparent conductive oxide by heat treatment (S30) and transferring a composite electrode including the graphene and the transparent conductive oxide onto a final substrate (S40). Hereinafter, each step will be described with reference to fig. 12 and the corresponding drawings.

Fig. 13 to 20 are schematic sectional views illustrating respective steps of manufacturing a graphene composite electrode.

As shown in fig. 13, in order to manufacture a composite electrode including graphene, graphene 20 is formed on the catalytic metal 10 (S20).

The catalytic metal 10 may be a metal such as Ni, Co, Fe, Pt, Au, Al, Cr, Cu, Mg, Mn, Mo, Rh, Si, Ta, Ti, W, U, V, or Zr, and may be a single layer of any one thereof or an alloy of at least two thereof.

Methods of producing graphene 20 include chemical vapor deposition, such as thermal Chemical Vapor Deposition (CVD), inductively coupled plasma chemical vapor deposition (ICP-CVD), Plasma Enhanced Chemical Vapor Deposition (PECVD), and microwave CVD. In addition, various methods such as Rapid Thermal Annealing (RTA), Atomic Layer Deposition (ALD), and Physical Vapor Deposition (PVD) may be used.

For example, chemical vapor deposition is a method of growing graphene 3 by placing a catalytic metal 10 in a chamber (not shown), supplying a carbon source thereto, and providing appropriate growth conditions.

For example, the carbon source may be in a gaseous state such as methane (CH)₄) Or acetylene (C)₂H₂) Or a solid such as a powder or polymer, or a liquid such as a bubbled alcohol supply.

Hereinafter, the use of copper (Cu) as the catalytic metal 10 and the use of methane (CH) will be described₄) As an example of the carbon source.

When methane gas is supplied onto the catalytic metal 10 under a hydrogen atmosphere while maintaining an appropriate temperature, hydrogen reacts with methane, forming graphene 20 on the catalytic metal 10. The formation of the graphene 20 may be performed at a temperature of about 300 ℃ to about 1,500 ℃.

At this time, when there is no space on the lower surface of the catalytic metal 10, the graphene 20 can be formed only on the upper surface of the catalytic metal 10. On the other hand, when there is a space on the lower surface of the catalytic metal 10, the graphene 20 may be formed on both surfaces of the catalytic metal 10.

Copper as the catalytic metal 10 may facilitate the formation of single-layer graphene into low solid solubility. The graphene 20 may be formed directly on the catalytic metal 10.

The catalyst metal 10 may be supplied in a sheet form, but may be continuously supplied using a roll, or a copper foil having a thickness of about 10 μm to 10mm may be used as the catalyst metal 10. That is, the graphene 20 may be formed on the catalytic metal 10 using a roll-to-roll process.

When the graphene 20 obtained by the foregoing process is formed on both surfaces as described above, the graphene 20 formed on one surface of the catalytic metal 10 may be removed.

By this process, as shown in fig. 13, graphene 20 may be formed on one surface of the catalytic metal 10.

Then, doping of the graphene 20 is performed (S11).

By such a doping process (S11), the conductivity of the graphene 20 may be improved. That is, the grain defects caused by the catalytic metal 10 (defects caused by grain boundaries of the metal, etc.) may cause the electrical conductivity of the graphene 20 to deteriorate. In this regard, the material of the graphene 20 is replaced with a dopant material that can generate carriers. Therefore, the carrier density can be increased.

In addition, specifically, examples of such a dopantComprising NO₂BF₄、NOBF₄、NO₂SbF₆、HCl、H₂PO₄、CH₃COOH、H₂SO₄、HNO₃PVDF, perfluorosulfonic acid, AuCl₃、SOCl₂、Br₂、CH₃NO₂One or more of dichlorodicyanoquinone, oxone, dimyristoyl phosphatidylinositol and trifluoromethanesulfonyl imide.

Fig. 14 shows a transparent conductive layer 31 formed on the graphene 20. Accordingly, forming a transparent conductive layer on the graphene 20 using the transparent conductive oxide is performed (S20).

Here, the Transparent Conductive Oxide (TCO) may include at least one of Indium Tin Oxide (ITO), Indium Zinc Oxide (IZO), zinc oxide (ZnO), gallium-doped zinc oxide (GZO), and aluminum-doped zinc oxide (AZO).

Among them, ITO is prepared by carrying out SnO₂Is dissolved In₂O₃The resulting material, which is an oxide having low resistance and stable at room temperature, exhibits excellent transmittance in the visible region while exhibiting high reflectance in the infrared region.

Then, crystallization of the transparent conductive oxide by heat treatment is performed (S30).

The step of crystallizing the transparent conductive oxide by heat treatment (S30) may be performed at a temperature of 150 to 400 ℃.

Such crystallization S30 can improve the crystallinity of the transparent conductive layer 31 and reduce the resistance. Accordingly, as shown in fig. 15, the crystallized transparent conductive layer 30 may be disposed on the graphene 20.

The formation (S20) and crystallization (S30) of the transparent conductive layer 31 can be performed by using a sputtering apparatus shown in fig. 21.

Fig. 21 is a schematic view showing a process of forming a transparent conductive layer according to the present invention.

First, the degree of vacuum of the chamber 100 was made to 10 mTorr by a first vacuum pump (rotary pump; 110), and second, the degree of vacuum was made to 10 mTorr by a second vacuum pump (diffusion pump; 120)3×10^-6Millitorr.

The RF power supply 150 has a power of 300W or more, and the power can be adjusted upward or downward. The applied frequency is typically about 14MHz, which can be adjusted up or down.

Ar implantation may be performed to generate plasma, and a small amount of oxygen may be implanted together with Ar to perform crystallization (S30).

By this process, the ITO 30 may be formed on the graphene 20 formed on the catalytic metal 10, as shown in fig. 21, the graphene 20 being omitted.

When power is applied from the RF power supply 150 to generate plasma on one side of the target 130, the target 130 evaporates and forms ITO as the transparent conductive layer 30 on the graphene 20. The permanent magnet 140 may be disposed under the target 130.

Hereinafter, an example in which the crystallized transparent conductive layer 30 is an ITO layer will be described.

The transparent conductive layer 30 formed on the graphene 20 can produce a transparent composite electrode. That is, a transparent composite electrode having low resistance can be formed by organic/inorganic mixing of the graphene 20 and the ITO layer 30.

Such a composite electrode is suitable for use in currently industrially available sputtering methods. This may result in 1/5 reducing the amount of ITO used. This is because all the conditions of the transparent electrode are satisfied although the composite electrode is formed to a small thickness.

In addition, the ITO layer 30 may function as a protective film for the graphene 20. When the graphene 20 is doped, the doping effect may be maintained for a longer time.

Then, the transfer of the composite electrode including the graphene and the transparent conductive oxide to a final substrate is performed (S40).

The transfer (S40) may be performed in general by two methods.

First, a temporary support layer is used.

For this purpose, as shown in fig. 16, a support layer is disposed on the ITO layer 30. The support layer 40 may be adhered to or formed directly on the ITO layer 30. The support layer 40 adhered to the ITO layer 30 may be a transfer film. The transfer film includes an adhesive layer and can be easily removed from the ITO layer 30 because it loses adhesiveness upon subsequent application of heat or light.

Additionally, the adhesive layer may be a processable adhesive. That is, the adhesive layer can be easily released during or after processing, and no residue is left even after the release.

Next, as shown in fig. 17, the catalytic metal 10 is removed.

The final substrate 50 may then adhere to the surface from which the catalytic metal 10 was removed. In some cases, the final substrate 50 may be formed directly on the surface from which the catalytic metal 10 is removed.

The final substrate 50 may refer to a layer that may be applied to an electronic device together with the graphene 20.

That is, the final substrate 50 may be a transparent or opaque substrate that may be directly used for various display devices, and may be a substrate that is directly used for devices such as a touch panel.

The final substrate 50 may be a polymer material such as polyethylene terephthalate (PET), triacetyl cellulose (TAC), and Polycarbonate (PC), or a semiconductor wafer such as silicon (Si). In addition, any member may be used without limitation as long as it is a transparent or opaque film.

The method may then include removing the support layer 40. When the support layer 40 is removed, the composite electrode comprising the graphene 20 and ITO layer 30 is disposed on the final substrate 50, as shown in fig. 18.

Meanwhile, in case of not using a support layer, the final substrate 50 may be directly adhered to the ITO layer 30 or formed on the ITO layer 30 for transfer.

The catalytic metal 10 may then be removed.

By this transfer method, the composite electrode including the graphene 20 and the ITO layer 30 may be disposed on the final substrate 50. However, as shown in fig. 20, the ITO layer 30 is disposed directly on the final substrate 50.

In this way, a flexible transparent electrode can be produced with the composite electrode transferred to the final substrate 50. That is, the composite electrode imparts both conductivity and flexibility, thereby eliminating the limitations of flexible displays that cannot be overcome with an ITO layer alone.

As described above, the present process is applicable to an ITO roll-to-roll process, and may be used in combination with a roll-to-roll based graphene synthesis process.

By this intermixing of the two-dimensional materials graphene 20 and ITO layer 30, the transparent composite electrode can be produced, and the composite electrode comprising graphene 20 comprises an organic material (graphene), and in particular, thereby exhibits excellent adhesion to an organic EL display.

Accordingly, as shown in fig. 20, the method may further include forming an organic EL layer 60 on the graphene 20. Thus, the composite electrode produced according to the present invention can be used as a transparent electrode, particularly a flexible electrode, of an organic EL display. However, the object to be applied is not limited to the organic EL display.

As described above, the composite electrode including the graphene 20 and the ITO layer 30 may be heat-treated at a temperature of 150 ℃ to 400 ℃, thereby greatly improving conductivity. In the case where only ITO disposed on a conventional polymer substrate is used for the transparent electrode, heat treatment at 150 ℃ or higher cannot be performed. Therefore, the transparent electrode produced according to the present invention can greatly improve the conductivity as compared with the conventional case.

In addition, as a result, the thickness of the electrode can be reduced to half or less at the same conductivity, which means that the material used for the electrode is reduced.

Meanwhile, although the embodiments of the present invention disclosed in the specification and the drawings have been provided as specific examples for illustrative purposes, they should not be construed as limiting the scope of the present invention. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention.

[ INDUSTRIAL APPLICABILITY ]

The surface of various substrates can be modified rapidly and at low cost using a polymer layer comprising an organic precursor.

Graphene disposed on a surface-modified substrate may exhibit improved electrical properties.

Meanwhile, the transparent conductive layer formed on the graphene may produce a transparent composite electrode. That is, a transparent composite electrode having low resistance can be formed by organic/inorganic mixing of graphene and an ITO layer.

Claims

1. A method of modifying doped graphene using a substrate surface, comprising:

forming a precursor polymer layer for doping on a substrate; and

disposing graphene on the substrate provided with the precursor polymer layer,

wherein the precursor polymer layer comprises a precursor having plasma treated cyclohexane.

2. The method of claim 1, wherein the precursor polymer layer comprises a precursor having a methyl group as an end group.

3. The method of claim 1, wherein the substrate is a polymer substrate.

4. The method of claim 3, wherein the polymer substrate comprises at least one of polyethylene terephthalate (PET), triacetyl cellulose (TAC), and Polycarbonate (PC).

5. The method of claim 1, wherein the forming of the precursor polymer layer is performed using plasma enhanced chemical vapor deposition.

6. The method of claim 1, further comprising: doping the graphene.

7. A graphene structure comprising:

a substrate;

a precursor polymer layer having a methyl group disposed on the substrate; and

a graphene disposed on the precursor polymer layer,

8. The graphene structure of claim 7, wherein the substrate comprises at least one of polyethylene terephthalate (PET), triacetyl cellulose (TAC), and Polycarbonate (PC).